Hoarding disorder is a mental disorder characterized by persistent difficulty in parting with possessions and engaging in excessive acquisition of items that are not needed or for which no space is available. This results in severely cluttered living spaces, distress, and impairment in personal, family, social, educational, occupational, or other important areas of functioning. People with hoarding disorder have persistent difficulty getting rid of or parting with possessions due to a perceived need to save the items. Attempts to part with possessions create considerable distress. Hoarding disorder can cause problems in relationships, social and work activities, and other important areas of functioning. It can also lead to health and safety concerns, such as fire hazards, tripping hazards, and health code violations. Hoarding disorder is different from collecting, as people who have collections carefully search out specific items, organize them, and display their collections, while collections can be large, they arent usually cluttered, and they dont cause the distress and problems functioning that are part of hoarding disorder.

Hoarding disorder can be a symptom of another condition, such as mobility problems, learning disabilities, or dementia. Many people with hoarding disorder also experience other mental disorders, including depression, anxiety disorders, attention deficit/hyperactivity disorder, or alcohol use disorder. Hoarding disorder is often difficult to treat and can take years due to several factors, including low motivation, poor insight, significant clutter accumulation, and difficulty changing behaviors when the person has been engaging in them for decades.